The present invention relates to cigarettes which burn tobacco, and in particular to cigarettes, which when smoked, generate low amounts of sidestream "tar" and sustain smolder at least during FTC smoking conditions.
Popular smoking articles, such as cigarettes, have a substantially cylindrical rod shaped structure and include a charge of smokable material such as shredded tobacco (e.g., in cut filler form) surrounded by a paper wrapper thereby forming a so-called "tobacco rod." Normally, a cigarette has a cylindrical filter element aligned in an end-to-end relationship with the tobacco rod. Typically, a filter element includes cellulose acetate tow circumscribed by plug wrap, and is attached to the tobacco rod using a circumscribing tipping material. It also has become desirable to perforate the tipping material and plug wrap, in order to provide dilution of drawn mainstream smoke with ambient air.
Cigarettes are employed by the smoker by lighting one end thereof and burning the tobacco rod. The smoker then receives mainstream smoke into his/her mouth by drawing on the opposite end (e.g., the filter end) of the cigarette. During the time that the cigarette is not being drawn upon by the smoker, it remains burning, and sidestream smoke is generated. Sidestream smoke is smoke which directly enters the atmosphere from the lit end of the cigarette. Sidestream smoke diffuses into the atmosphere, and the characteristic visible nature thereof may be perceived negatively by some individuals. Thus, certain cigarette smokers have indicated a desire to decrease the levels of visible sidestream smoke generated by their cigarettes.
The relative amount of visible sidestream smoke generated by a burning cigarette is related to the amount of sidestream "tar" generated by that burning cigarette. Typical cigarettes of about 84 mm length (e.g., having a tobacco rod length of about 57 mm and a filter element length of about 27 mm) often yield about 25 to about 35 mg of sidestream "tar" per cigarette. See, Proctor, et al., Analyst, Vol. 113, p. 1509 (1988), for an apparatus and technique for determining the sidestream "tar" of a cigarette.
Numerous cigarettes which reportedly yield relatively low levels of visible sidestream smoke have been proposed. See, for example, U.S. Pat. Nos. 4,108,151 to Martin; 4,225,636 to Cline; 4,231,377 to Cline; 4,407,308 to Baker; 4,420,002 to Cline; 4,450,847 to Owens; 4,461,311 to Mathews; 4,561,454 to Guess; 4,624,268 to Baker, et al.; 4,637,410 to Luke; 4,805,644 to Hampl, Jr., et al.; 4,881,557 to Martin; 4,915,118 to Kaufman, et al.; 4,924,888 to Perfetti, et al.; 4,941,485 to Perfetti, et al. and 4,998,541 to Perfetti, et al.; as well as European Patent Application No. 402,059.
It would be desirable for the cigarette manufacturer to provide a good tasting cigarette which (i) provides good smoking satisfaction, (ii) sustains smolder at least during FTC smoking conditions, and (iii) generates low levels of sidestream "tar" and hence low levels of visible sidestream smoke.